The Long Term Evolution-Unlicensed (LTE-U) refers to deployment of the LTE in an unlicensed spectrum to meet the increasing capacity requirements of LTE systems and improve the efficiency of the utilization of the unlicensed spectrum, and is a possible important direction of evolution for the LTE and future wireless communications. In the design of the LTE-U, it needs to consider how to fairly compete for the unlicensed spectrum with different systems such as WiFi, radar, etc. and the same system such as the LTE-U for data transmission.
According to the presentation of the 3GPP standard conference, the LTE-U system may also be referred to as an LTE Licensed Assisted Access (LAA) system for a licensed carrier assisted scenario. Currently, there are the following manners for the LTE-U to utilize the unlicensed spectrum: Carrier Aggregation Supplemental Downlink (CA SDL), Carrier Aggregation Time Division Duplex (CA TDL), and Standalone manners. Herein, the CA SDL is the mainstream manner at present, and in the related scheme, a base station can only transmit downlink data without uplink reception. That is, the base station can only receive a measurement quantity reported by a UE based on a licensed carrier, which is not timely enough. An existing delay may influence the competition for the unlicensed carrier with WiFi, and during within this time period, WiFi may have preempted resources.
With respect to this problem, currently, the Time Division Multiplexing (TDM) manner is primarily used for transmission of signals. For example, a half of a radio frame is occupied and the remaining half thereof is reserved for use by WiFi. This means that a mechanism of monitoring first and then speaking is not used, which can influence other systems that use unlicensed carriers, such as WiFi, thereby resulting in the problem of unfair use of the unlicensed carrier spectrum.